Air conditioning systems are routinely employed within automobiles and other vehicles for creating comfortable conditions within the passenger compartment for the vehicle occupants. At outside temperatures above about 70.degree. F., it is difficult to maintain a comfortable passenger compartment temperature without first cooling the air that is being blown into the passenger compartment.
Typically, cooling of the air is accomplished by first compressing an appropriate refrigerant, such as the fluorocarbon known generally as Freon, or some other alternative refrigerant. Within an automobile, the engine-driven compressor compresses the vaporized refrigerant, thereby significantly raising the temperature of the refrigerant. The refrigerant then flows into a condenser where it is cooled and returned to its liquid state; thus, the heat added to the refrigerant in the compressor is transferred out of the system. The cooled liquid refrigerant is then sprayed through a thermal expansion valve into an evaporator where it is again vaporized. The heat of vaporization required for vaporizing the refrigerant is drawn from the incoming outside air, which is blown through the evaporator. Excess humidity contained within the incoming air is removed as condensation on the evaporator, therefore also drying the incoming air. The cooled, dry air then enters the passenger compartment of the vehicle, while the refrigerant is drawn back to the compressor where it can be again compressed and the cycle repeated.
In this type of automotive air conditioning system, it is common practice to employ a receiver-dehydrator device between the condenser and the thermal expansion valve. The purpose of such a device is to remove any remaining moisture from circulation by the use of a desiccant which is provided within the receiver-dehydrator and to ensure delivery of the refrigerant in a liquid phase to the expansion valve.
Previously, several receiver-dehydrator designs have been proposed for satisfying these design requirements. Generally, the receiver-dehydrator assembly constitutes a cylindrical container having an inlet and an outlet for connecting into the refrigerant circuit. The desiccant is typically contained in a bag which fits into the bottom portion of the cylindrical container. The construction of the receiver-dehydrator assembly is such that refrigerant flow is directed through the desiccant so that the desiccant can perform its intended function of removing moisture from the refrigerant.
Typically, when aluminum or aluminum alloy materials are being used, the fabrication of such receiver-dehydrator assemblies includes the joining of the inlet and outlet connectors to the outside canister assembly by brazing. The brazing process is problematic in that there may be braze residue remaining in the joined regions which may lead to contamination or pinhole leaks within the assembly, thereby potentially causing a loss in the pressurized refrigerant charge. Alternatively, for aluminum or steel materials, arc welding may be used to join the connectors to the outside canister, however the arc welding process is also problematic in that it may result in detrimental dimensional changes to the assembly.
In addition, often the canister will be formed from two separate parts, such as two half shells or a base and a cap, that are joined together around a circular seam. The two parts are typically drawn or stamped. The various internal components of the assembly are assembled into the two separate canister parts before they are seamed together. The seaming process is also particularly vulnerable to the formation of detrimental pinhole leaks if any residue inadvertently remains at the joined surfaces. Further, misalignment of the two shells may occur.
Therefore, although the receiver-dehydrator assembly has become a necessary component within automobile air conditioning systems, the manufacturing processes used to form such assemblies have been less than ideal. Accordingly, the industry needs a method for manufacturing these receiver-dehydrator assemblies which avoids the shortcomings of the prior art. In particular it would be desirable to provide a receiver-dehydrator assembly which is manufactured from one integral piece so that the assembly is seamless to avoid the possibility of leakage, and which is characterized by minimal dimensional distortion resulting from the connection of the inlet and outlet connectors, while retaining the overall integrity of the assembly. Further, it would also be particularly advantageous if the assembly were universally adaptable to a variety of inlet/outlet configurations for enhanced versatility of the assembly.